Anti-atherosclerotic activity of Betulinic acid loaded polyvinyl alcohol/methylacrylate grafted Lignin polymer in high fat diet induced atherosclerosis model rats

Betulinic acid is one such natural pentacyclic triterpenoid compound, holding various pharmacological properties but its poor bioavailability is the only limitation. One of the biological macromolecules such as Lignin is a plant-derived aromatic, eco-friendly and low-cost polymer that certainly self-assembles into nano-sized colloids. Therefore, onto the current investigation, we increased the bioavailability of betulinic acid by coating on to a nanopolymer prepared with poly vinyl alcohol, lignins and methyl acrylate. Betulinic acid loaded polyvinyl alcohol/ethylacrylate grafted Lignin polymer (PVA/Lig-g-MA) nanoformulation was characterized using FTIR, XRD, SEM and TEM analysis and also the drug entrapment, in vitro drug releasing capacity was done to examine the efficiency of the nanoformulation of a drug. The MTT assay was evaluated the cytotoxicity of synthesized nanoformulation against normal endothelial cells HUVEC and HAPEC to confirm the side effects of the drug. The anti-atherosclerotic property of the nanoformulation was ascertained in both in vitro condition (with HUVEC and HPAEC) and in vivo studies (with Wistar rats). As a result, the characterization studies and in vitro studies clearly confirmed the Betulinic acid loaded PVA/Lig-g-MA nanoformulation is an ideal nanopolymer and it doesn’t cause any cytotoxic effect in normal endothelial cells. It also decreased the lipopolysaccharides induced inflammation through the down-regulation of NFκB and MAP/JNK signaling molecule expressions. Following in vivo results confirmed the synthesized nanoformulation effectively decreased the hyperchlostremia, inflammation and vasoconstriction, which induced over high fat diet. The results of histopathological analysis of cardiac tissues also confirmed the cardioprotective role of synthesized nanoformulation. Overall, both the in vitro and in vivo studies authentically proven the Betulinic acid loaded PVA/Lig-g-MA nanoformulation would be a potent cost effective anti-atherosclerotic nanodrug.     

反应温度对蒙脱石载银量及其缓释性能的影响

以钠基蒙脱石(Na-MMT)为载体,氧化银与氨水反应形成的银氨络合物[Ag(NH₃)₂OH]为前驱体,通过离子交换和三乙醇胺(TEA)还原两步法制备了载银蒙脱石(Ag-MMT)。 用佛尔哈德法测定了载银蒙脱石(Ag-MMT)的载银量,探讨了反应温度对MMT 载银量及其缓释性能的影响,并用FI-IR、XRD等技术手段对Na-MMT和Ag-MMT的结构进行了表征。 结果表明,在蒙脱石与Ag⁺的质量比为20:1、离子交换时间为1 h、反应温度50 ℃,然后再加入三乙醇胺和聚乙烯吡咯烷酮,50 ℃下反应2 h,MMT的载银量最大,银的利用率达到86.89%,释放时间最持久,并且MMT的层状结构没有被破坏。     

轴向移动系统的参数振动问题研究进展

对近二十年来轴向移动系统(移动弦，移动梁和移动带等)的参数振动研究进展进行了详细的评述，特别关注了轴向张紧力和移动速度随时间改变时轴向移动系统的参数振动特性和稳定性等问题。文章首先讨论了所研究问题的控制方程。然后详细说明了目前研究中人们较为关注的几个重点问题，如参数激励的形式，求解方法和所研究的问题等。接着在其后的两节中，分别评述了在张紧力和移动速度随时间变化时，轴向移动弦和轴向移动梁的振动问题近年来的研究进展，详细、深入讨论了模型的类型、张紧力和轴向移动速度随时间变化的形式以及在研究中使用的解题方法和系统的振动特性(振动响应、固有频率和动态稳定性)等；最后给出了在此领域今后研究中应关注的问题。     

轴心受压H型截面钢柱火灾行为的试验研究

本文对4根H型截面钢柱进行了火灾行为的试验研究。全部火灾试验采用自行研制的火灾试验炉,试验结果表明炉子性能稳定,使用方便。试验采用足尺试验形式,柱长3300mm。钢柱轴心受压,其中两个限制轴向变形,另两个不限制轴向变形。柱两端采用单向刀口支座,允许钢柱绕强轴转动。钢柱试验中考虑荷载大小和是否限制轴向变形两个因素。通过试验,得出了钢柱在火灾下的侧向变形和轴向变形随温度变化情况。试验证明:钢柱受火时,轴向变形明显的分为膨胀阶段和压缩阶段。压缩阶段很短,一旦进入压缩阶段,钢柱很快破坏。钢柱受到的外加荷载越大,其极限温度越低。限制轴向变形的钢柱极限温度降低。试验研究为今后钢结构火灾行为研究提供了依据。     

Asymptotic Axially Symmetric Deformations for Perfectly Elastic Neo-Hookean and Mooney Materials

For axially symmetric deformations of the perfectly elastic neo-Hookean and Mooney materials, formal series solutions are determined in terms of expansions in appropriate powers of 1/R, where R is the cylindrical polar coordinate for the material coordinates. Remarkably, for both the neo-Hookean and Mooney materials, the first three terms of such expansions can be completely determined analytically in terms of elementary integrals. From the incompressibility condition and the equilibrium equations, the six unknown deformation functions, appearing in the first three terms can be reduced to five formal integrations involving in total seven arbitrary constants A, B, C, D, E, H and k ², and a further five integration constants, making a total of 12 integration constants for the deformation field. The solutions obtained for the neo-Hookean material are applied to the problem of the axial compression of a cylindrical rubber tube which has bonded metal end-plates. The solution so determined is approximate in two senses; namely as an approximate solution of the governing equations and for which the stress free and displacement boundary conditions are satisfied in an average manner only. The resulting load-deflection relation is shown graphically. The solution so determined, although approximate, attempts to solve a problem not previously tackled in the literature.      

钢轴心受压构件截面的直接计算法

根据钢结构设计原理，依据现行国家标准《钢结构设计规范》（ＧＢＪ１７ ８８），通过计算构件合适长细比λ，直接进行钢轴心受压构件截面尺寸设计．     

DYNAMIC STABILITY OF AXIALLY MOVING VISCOELASTIC BEAMS WITH PULSATING SPEED

IntroductionThe class of systems with axially moving materials involves power transmission chains,band saw blades and paper sheets during processing. Vibration of such systems is generallyundesirable. The traveling tensioned Euler-Bernoulli beam is the pr…     

加筋板结构的大变形

本文对受均布载荷，具有一根纵向加筋多根横向加筋的加筋板结构的残余变形导出了近似理论分析方法。从假设变形模态出发，依据极限分析原理获得可能变形模态和模态判别条件。在变形分析中，计及膜力（轴力）影响，但忽略弹性影响，得到了各变形模态下的残余变形估算公式。最后根据本文的理论分析方法和ＡＤＩＮＡ程序作了实例计算，两者的变形模态和最大残余变形均十分一致     

Asymptotic Modeling of Nonlinear Wave Processes in Shock‐Loaded Elastoplastic Materials

Nonlinear wave processes in shockloaded elastoplastic materials are modeled. A comparison of the results obtained with experimental data and numerical solutions of exact systems of dynamic equations shows that the model equations proposed qualitatively describe the stressdistribution evolution in both the elasticflow and plasticflow regions and can be used to solve one and twodimensional problems of pulsed deformation and fracture of elastoplastic media.     

纵横载荷作用下功能梯度梁的弯曲和过屈曲

基于一阶非线性梁理论和物理中面概念,导出了纵横向载荷作用下功能梯度材料(FGM)梁非线性弯曲和过屈曲问题的控制方程,并获得了该问题的精确解;据此解研究了梯度材料性质、外载荷、横向剪切变形以及边界条件等因素对功能梯度材料梁非线性力学行为的影响,分析中假设功能梯度材料性质只沿梁厚度方向,并按成分含量的幂指数函数形式变化。结果表明:纵横载荷共同作用下,功能梯度梁的弯曲构形将有无限多个;随着梯度指数的增大,梁的变形减小,临界载荷升高;随着长高比的增大,横向剪切变形的影响减小。